harrington



DeC- 2 1941- F. T. HARRINGTON POWER TRANSMISSION Original Filed Dec. 29, 1958 2 Sheets-Sheet l a J FIG a INVENTOR FERRIS T. HARRINGTON BY ATTORNEY 2 Sheets-SheefI 2 F. T. HARRINGTON POWER TRANSMISSION kmM 9 INVENTOR 1 LL. FERR|s T. HARRINGTON Original Filed Dec.

Dec. 2, 1941.

ATTORN EY .,Reissued Dec. 2, 1941 l UNITED STATES Ferris '.l.

tion of Michigan 'z claims.

v This invention relates to power transmissions, particularly to those of the type comprising two or vmore iiuid pressure energy translating devices one of which may function as a pump and another as a iluid motor.

The invention is more particularly concerned with a power transmission system particularly adapted for actuating a reciprocating slide such as is commonly used on machine tools of various types.

Itis an object of the present invention to proing an improved posite sides ofthe pressure of only two two-position valves.

lMore speciilcally it is an object of the invention to provide a power transmission system of this character wherein a reciprocating lmachine of operation, including 'a rapid advance, a feed advance, a rapid` return and a stop. l

It is also an object to provide these features byV apparatus of a much simpler and more reli-` able nature than and to permit of the entire system to be controlled remotely throughv the use of but Atwo 'electrical actuators.

Further objects and advantages ofthe present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form oi the present invention is clearly shown.

l In the drawings: y A y Figure 1 is a diagrammatic view of a power transmission system incorporating a preferred form of the present invention.

Figure 2 is a diagrammatic cross sectional lview of a control panel forming part ofthe mechanism in Figure l.

Figure 3 is a top view, and Figure 5 is an the two side sections being displaced for clearness of illustration, these three gures being arranged in` orthographic projection on the sheet. A

Figure 6 is an end view ofthe backing platefor the control panel.

Figure I is a simplliledoiagram o1 the hydraulic circuit.

Figure 8 is a table `oi the valve positions with reference to the circuit oi- Figure 7. 4

Referring now to Figure 1, there is shown a pump i driven by a prime mover such as an electric motor i2 to withdraw iiuid from'a tank I6 through a suction conduit I4. Fluid is delivered Figure 4 is a front view,

livery conduit vde a hydraulic power transmission system havr main circuit capable of providing four dierent paths for fluid between opsourcev by the use toolslide may be subject to four different phases has heretofore been possible end view of the control panel,

Re. V21,963

PATENT "ien-lcs roWEa TRANSMISSION l Harrington, Detroit, Mich., assigner to Vickers Incorporated, Detroit, Mich., a corpora- Original No. 2,210,665, dated August 6, 1940, Serial December 29, 1938. Application for reissue October 1, 1941, Serial No. 413,222

through a delivery conduit I6, a relief valve 20 of conventional construction being provided for by-passing fluid to the tank through a return conduit 22 whenever `a predetermined pressure is exceeded in the delivery conduit I6. The de- |6 leads to a port 24 in the center section 26 of the control panel 26. The latter has side sections 36 and 32 containing solenoidoperated pilot valves later to be described.

A port 34 in the center section 26y connects by a conduit 36 with the tank. The center section 26 is also provided/with cylinder ports 36 and 46 which connect by conduits 42 and 44 with the upper and lower ends of a cylinder 46, .The latter carries a slidable piston 46 having a rod 56 to which is attached the load device 52.i Secured on an upwardly extending arm 54 are three tripping dogs 56, 56 and 60 'adapted to actuate limit switches 62, 64 and 66 respectively when the load device 52 is at the top, mid portion, and bottom positions respectively.

' For thepurpose of controlling the energization of the solenoids in sections 36 and 32 an electric circuit is provided. A momentary contact push button switch 66 is adapted when depressed to connect Line L1 by conductor 16 with the operating coil of a holding relay 12, the other side of which is connected to line cuit 14 extends through the normally closed contacts of a double-throw push button switch 16 and by a conductor 16 through limit switch 66 v. and to Line L1. Thus, when the switch 66 is momentarily closed and the relay 12 is lifted, the holding circuit is established provided that the switch 16 is not depressed and limit switch 66 is in its normally closed position. Opening of either switch 16 or switch 66 will deenergize the relay 12 and permit the latter to drop. The controlled circuit of relay 12'extends from the conductor 14 through a conductor BILto the solenoid in section 32, the other side of which is connected to line I F. Thus, whenever relay 12 is raised, the solenoid in section 32 isenergized.

- The normally open contacts of the switch 16 4b are connected in a circuit extending from line L1 by conductor 62 through the. left-hand contacts of limit switch 62 and by conductors 64 and 66 to the operatingA coil of a holding relay 86. The relay 66 is normally initially energized by closure of the normally open limit switch 64 4which when closed` establishes a circuit 'from line L1 through conductor 61 and conductor 66 tothe coil of relay 66. The holding circuit of the latand 62 to the right-hand U. The holding cir- Y 52 and thence to line L1.

- circuit is broken by opening of the limit switch l 48 approaches the bottom of its stroke the dog 50 f y nicates with the discharge chamber o'f a in the blocks 28, 80 and 82 is indicated in the and spring |28, the. right-hand face ofthe and |52 of valve |48 connect by a conduit |54 with the tank conduit |08. The other cylinder port |58 connects by a conduit |58 with apport of a foot valve |52. 'I'he latter comprises a two-land spool |84 biased to the left by a spring |56 in which position the spool blocks communication between port |88 and'a port |88.

Thus, whenever switch 15 is depressed and the limit switch 52 is in its normally closed position, the relay 88 will be raised and establish its holding circuit, thus maintaining the relay `raised until the holding c 62.l The controlled circuit of relay 88 extends from conductor 82 by a conductor 84 to the sole- The left-hand end of the valve communicates noid in section 30, the other side of which is conwith the .conduit ||2 through a' branch conduit nected to line L2. Thus the relay 88 when lifted v |10 so that whenever pressure exists in conduit energiz'es the solenoid in section 80. ||2 sufficient to overcome the force of spring It will be seen that the electric circuit above |88 the spool |84 is shifted to the right to condescribed operates when the starting button 88 neet the ports |50 and |54. Port |58 and the is depressed to lift the relay 12 which establishes right-hand end of the valve chamber connec itsvown holding circuit and also establishes a. cir- L, by a conduit |12 to the tank conduit |54. cuit from line L1 through limit switch 55, con- The spools |14 andl |15 of the valves |02 and ductor 18, switch 18, conductor 14 and conductor |40 are adapted to be shifted by hydraulic presto the solenoid in section 82. This, as will be sure admitted and exhausted to and trom their described later. causes downward movementof end chambers under the control oi' the pilot the piston 48 carrying the dog rod 54. During m, valves which are disposed in the side sections the nrst part or tnismcvemcnt the dog 5s passes 30 and 32- For this purpose a branch conduit oiI from th'e switch 52 permitting the latter to |18 extends from the pressure line -88 to the close but not energizing the rel-ay 88 due to the opposite faces of the center section 25 and breaks in the circuit at switch 15. At some point through the side sections 88 and 82 to the pr in/the mid portion of the travel the dog 58 con- 2.) sure ports |810 and |82 of solenoid-operated fourtacts switch 84 energizing the relay 88 through. way pilot valves |84 and |88 respectively. p conductors l81 and 85 and lifting'the same to es- A cylinder port |88 of valve |84 connects by tablish its holding circuit and to establish the a conduit |80 with the left-h'and end chamber controlled circuit extending from line L1 through of the valve |40- The other cylinder Port Il! switch 82, conductors -82 and 84 to the solenoid 3 connects by a conduit |84. with the right-hand in section 8o. This, as will be later described, end chamber of the valve |45. The upper end causes the piston 48 to continue its descent at s. of the valve |84 and drain chambers |85 and slower or feed rate of movement. As the piston |88 formed in the spool 258 connect to tank by a conduit 202 and by a central bore 204 formed contacts the switch 58 opening the holding circuit 35 in the spool 288. for relay 12 and thus deenergizing the solenoid in The pilot valve |88 is identical in construction section 82.' This causes the piston 48 to ascend, to the pilot valve |84, its corresponding parts and when it reaches the top the dog 58 contacts being designated as follows: One cylinder Port the switch S2 opening the same and breaking` the 206 Connects by a cODdllit 20| with' the left-hand holding circuit for relay I8, thus deenergizing the 4U end of valve |02- Cylinder port III connects by solenoid in section 88. This causes the device to a conduit 2|2 with the right-hand end of valve come to'rest, |02. Drain chambers 2|4 and 2| 8 in the spool The internal construction of the panel 28 is 2 I8 connect to tank by a conduit 228 and a illustrated at Figure 2. The port 24 in the cenvcentral bore 222. The spools of the pilot valves ter section 28 -communicates by a conduit 98 45 are Spring biased downwardly by Spl'ihs 224 which' leads to the pressure port |00 of a pilotand 225 and have projecting stems 228 and 288 operated four-way valve generally designated as which mayl be lifted by the solenoids 282 and luz. The latter hastankports |04 and |06 which 234. 'Er'nersency manual operating stems 285 connect by "a conduit |08 with the port 84. One and 238 may be secured to the armatures 248 cylinder port ||8 connects by a conduit ||21with 50 and 2.42 respectively for manual lifting of either th'e cylinder port 88. The other cylinder Aport solenoid in case of power failure. The solenoids ||4 connects by a condultiii with a manually Izly zensclo'sed by angle-shaped cover plates adjustable throttle ||8..

On the opposite lsides the throttle commu- The relative disposition of the various valves 55 projected views constituting Figures `3, 4, and 5.

The throttle ||8 may be connected to a suitable indicator handle 248 on the front of the central section.v The ports 24, 84, 88 and 48 are pre1- hydrostatic valve |22 having an inlet port |24. The' valve |22 is under the control of apiston piston being subject to pressure in the conduit ||8 through a branch conduit |88 while the lefthand face of the piston is subject to pressure Y in the discharge chamber |20 through a conduit |82. Th'e action of the hydrostatic valve |22 and throttle lisis such as to maintain a iixed but adjustable rate of now therethrough independently oi pressure variations by maintaining a. i constant pressure drop across the throttle ||8.

The inlet port |24 of the hydrostatic `valve |22 connects by a conduit |84 with a conduit |88 leading to one cylinder port |88 of a pilot-operated four-way valve |48. A by-pass conduit |42 connects between conduits ||5 and |85 and contains a check valve |44 open tovfree now from conduit III to conduit |88.

=The pressure port |45'ot valve |48 connects by a conduit |48 with the port 48. The tank ports` erably brought out to the back face of the .center section 28 so that the latter may, if desired, be

mounted directly upon a machine frame having corresponding ports adapted to register therewith when the block 28 is fastened thereto.

For applications wh'ere the machine trame is not especially designed for direct mounting of ,the panei'on the frame, a backing plate 258 is provided for mounting the center section 25 and having cored passages therein which register with the ports in the back face ofthe center block 25 and lead to pipe connections 252 and 254 at one side and 258 and 258 at theother side.

Before considering the operation o! 'th'e hydraulic circuit as a whole, it will be understood that whenever solenoid 282 is deenergized, pressure duid from line 88 through conduit |19, port |80, 'port |99 and conduit |90 to the vleft-hand end of valve |40, shifting the latter to the right discharging oil from the right end through conduit |94, port |92, drain chamber |99,

v conduits 202 and |12 `to tank. When solenoid 232 is energzedthe connections are reversed to admit pressure to the right end of valve |40 and connect the left end to tank whereby the valve shifts to the left. Identical action takes place with regard to the solenoid 234 controlling the valve |02 so that when solenoid 234 is deenergized the valve is shifted to its right-hand posi` tion and when energized the valve is shifted to its left-hand position.

The operation of the main hydraulic circuit may be more easily understoodv by reference to `the simplifiedV circuit shown in Figure 7 and the table of valve positions shown in Figure 8. In Figure 7 the four-way valves |02 and |40 are illustrated as circles and the solenoid-operated pilot valves whichshift them have been omitted.

With the valves |02 and |40 in the position shown in the table of Figure 8 for the rapid advance function, the oil is withdrawn by the pump |,0 through conduit I4 and delivered through conduits I9 and 99 to port |00 of valve |02 where it is directed to port ||9 and through conduits ||2 and 42 to the head end of cylinder 46. Oil discharged from the rod end passes through conduits 44 and |49 to port |46 of valve |40 where it is delivered to port |56, through con- ,dui't |58, valve |62, and conduit |12l to tank.

Valve |62 is open at this time because pressure is transmitted from line ||2 through conduit |10 to open the valve. The outlet path under these conditions is shown by the dotted arrow 'I'he circuit just described is that established when4 solenoid 234 is energized and solenoid 232 is deenergized.

As the piston 48 reaches the point where dog 58 closes limit switch 64, the solenoid 232 becornes energized as previously described and valve |40 is shifted to the position for'feed asv shown in Figure 8. Under these conditions the owto the head end of the cylinder 46 is the same as before while the outlet path for fluid from the .rod end is now delivered from port |46.to port |38 and through conduits |36 and |34, iiow control valve |22-H9, conduit ||6,.ports ||4 and A|04 of valve |02, conduits |09- and 36 to tank.

This outlet path is indicated by the dotted arrow `2. Under these conditions the pisin 48 can shown for stop in Table 8. Under these conditions oil delivered bythe pump to port |38 of valve l|40 is transferred to the port |50 thereof and through conduit |54 to tank. The pump is thus by-passed through the outlet path indicated by the dotted arrow 4 at negligible pressure. It will be noted also that due to lack of pressure in line I2, the valve |62 moves to closed position, thus preventing downward travel of the piston 40 under its gravity bias.

The present control panel is so constructed that the pilot valves and solenoids for operating the same are arranged in the two side sections 30 and 32 which may be assembled to a center section 26 of one capacity or another, thus providing a flexible unit system wherein complete control `movements of the cylinder the latter is positively opened by pressure in the high side of the system and consequently there is no load imposed by the foot valve which the pump must overcome in order to move the piston 49. Thus the full capacity of the pump plus the gravity bias is available for effective work particularly during the feed portion of the cycle, and yet the valve |62` is effective to maintain the piston stationary against a gravity load of any magnitude.

' The present invention has been described in a form suitable foruse with a unitary power transmission system wherein a single pump feeds a single motor through the novel control panel describi d. It will be understood, however, that where a single pump feeds other apparatus in addition to that controlled by the present panel or where a separate pump unloading valve is used,

it may be undesirable to unload the pump when the valves |02 and |40 are in stop position. In such cases the valve |40 may be constructed as a three-way valve omitting theport |50. Preferably this is accomplished by substituting a different valve spool having its lands properly arranged so as to control ports |39, |46 and |56 in the manner disclosed but arranged to. block port |50 in all positions.

While 4the form of embodiment of the invention 4 as herein disclosed constitutes a preferred form,

, -it is to be understood that other lforms might be travel only as fast as the setting of the throttle ||8 dictates, and thisrate of flow is maintained by the action of the hydrostatic valve |22 independently of variations in the resisting load which the piston 48'must overcome.

As the piston reaches its lower limit the dog 60 opens the limit switch 66,.thus Adenergzing the solenoid 234 and shifting'the valve |02 to the position shown in Table 8 for rapid return. Under these conditions oil which is deliveredby the pump flows from port |00 to port I |4 of valve |02 through conduit ||6-, check valve |44, conduits |42 and |36, ports |38 and |46 of valve |40, and conduits |49 and 44 to the rod end of cylinder 46. Fluid delivered' from the headv end is discharged through conduits 42` and ||2, ports ||0 and |04 of valve |02, and conduits |09 and 96 to tank. This outlet'path is shown by the dotted arrow 3. Thus the piston 49 is caused to return upwardly at a rapid rate.

When the piston reaches its uppermost position the limit switch 62 is opened, thus deenergizing solenoid 232 to shift the valve |40 to the position 75 adopted, all coming within which follow.

What is claimed is as follows: l. In a fluid power transmission system the combination, with a single source of pressure the scope of the claims fluid 'having a single point of discharge, of afluid motor, iiuid supply and return conduits leading from and to the source of fluid, a pair of directional control valves each independently shiftable between only two positions and connected to one of said conduits, and branch conduits connecting said valves to each other and to the motor and forming with said valves four dif-` ferent. paths for fluid between opposite sides of y said source, one of said paths providing a by-pass through both valves around the source, the other three/paths providing iiow to and from the motor in bth directions including two diierently controlled paths between the motor and'the source,

in one direction.

2.- In a iiuid power 'transmission system the combination, with' a single source of pressure fluid having a single point of discharge, of a duid motor,l iiuid supply and return conduits leading from and to the source of iluid, a pair of directional control valves each independently shiftable between only two positions and connected to one of said conduits, and branch conduits connecting said valves to each other and to the motor and forming with said valves four diii'erent paths for fluid between opposite sides otsaid source including at least one path extending' through both valves between the motor and the source, one of said paths providing a by-pass around the source, the other three paths providing flow to and from` the motor in each direction with a ilow rate controller in one path.

3. In a uid power transmission system the combination, with a single source of pressure fluid having a single point of discharge, of a fluid :n.oes

posite sides of the motor, a iirst directional control valve having connections with said Supply and' return lconduits and with one of said motor supply and return conduits, means in one of said motor, iluid supply and return conduits leading from and to the source of fluid, a pair oi directional control valves each independently shiftable between only two positions and connected to one of. said conduits, and branch conduits connecting each of said valves both to the other valve and to the motor and forming with said valves fourdifferent paths for fluid between opposite sides of said source, one of said paths providing a by-pass around the source, the other three paths providing flow to and from the motor in 'both directions including two diierently controlled paths between the motor and, the source in one direction, one of which extends through both valves between the motor and the source.

4. In a uid power transmission system the combination with a source o1' pressure fluidincluding a pump, of fluid supply and return conduits leading from and to the source, a/iiuid motor, a pair. of motor conduits extending to opposite sides of themotor, a rst directional control valve having connections with said supply and return conduits and 'with one of said motor conduits, a second directional control valve having connections with the other motor conduit, with the iirst valve and with at least one of said supply and return conduits, means in one of said connections for producing a regulated reduced .rate oi' iiow therein, and means for shifting each of said valves independently between either oi' two positions to provide operation of the motor at one speed in either direction, at a different speed in one direction and to stop the motor.

5. In a iiuid power transmission system the combination, with a source of pressure iluid including apump, of iiuidsupply and return conduits leading from and in the source, a iiuid motor, a pair of motor conduits extending to opconnections i'or producing a regulated reduced rate of ow therein, and means including a pair of yieldably biased electric operators i'or shifting each of said valves independently between either of Atwo positions to provide operation of the motor at one speed in either direction, at a diil'erent speed in one direction and to stop the motor by selective energization of said electric operators.

l 6. In a fluid power transmission system the combination, with a single source of pressure iluid including a pump, and having a single point oi discharge, of fluid supply andreturn conduits leading from and to the source, a fluid motor, a pair of motor conduits extending to opposite sides ofthe motor, a pair oi directional control valves each independently movable between only two eifective positions, connections between each valve and at least vone of said lsupply and return' conduits, between each valve and the other valve and between each valve and at least one of the Amotor conduits, and means for shifting said valves selectively between said positions to provide three different operating circuits between the source and the motor and a fourth valve setting in which the motor is stopped.

,'7. In a iiuid power transmission system the combination, with a single source of pressure fluid including a pump, and having a single point of discharge, yoi' iluid supply and return conduits leading from and to the'source, a fluid motor, a pair of motor conduits extending to opposite sides oi' the motor, a pair of directional control valves each independently movable between only two effective pOsitions, connections between each valve and at least one of'said supply and return conduits, between each valve and the other valve and between'each valve and at least one oi' the An iotor conduits, and means for 'shifting said valves selectively between said positions to provide three diii'erent operating circuits between the source and the motor and a fourth valve setting in which the motor is stopped, vsaid valves and connections forming at least two iluid paths which extend between the source and one valve through the other valve independently of the motor.

FERRIS T. HARRmGTON. 

